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Managing glyphosate resistance in Australian cotton farming: modelling shows how to delay evolution and maintain long-term population control

Thornby, D. and Werth, J. and Walker, S. (2013) Managing glyphosate resistance in Australian cotton farming: modelling shows how to delay evolution and maintain long-term population control. Crop & Pasture Science, 64 (8). pp. 780-790. ISSN 1836-0947

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Article Link(s): http://dx.doi.org/10.1071/CP13109

Publisher URL: http://www.publish.csiro.au/nid/40.htm

Abstract

Glyphosate resistance is a rapidly developing threat to profitability in Australian cotton farming. Resistance causes an immediate reduction in the effectiveness of in-crop weed control in glyphosate-resistant transgenic cotton and summer fallows. Although strategies for delaying glyphosate resistance and those for managing resistant populations are qualitatively similar, the longer resistance can be delayed, the longer cotton growers will have choice over which tactics to apply and when to apply them. Effective strategies to avoid, delay, and manage resistance are thus of substantial value. We used a model of glyphosate resistance dynamics to perform simulations of resistance evolution in Sonchus oleraceus (common sowthistle) and Echinochloa colona (awnless barnyard grass) under a range of resistance prevention, delaying, and management strategies. From these simulations, we identified several elements that could contribute to effective glyphosate resistance prevention and management strategies. (i) Controlling glyphosate survivors is the most robust approach to delaying or preventing resistance. High-efficacy, high-frequency survivor control almost doubled the useful lifespan of glyphosate from 13 to 25 years even with glyphosate alone used in summer fallows. (ii) Two non-glyphosate tactics in-crop plus two in-summer fallows is the minimum intervention required for long-term delays in resistance evolution. (iii) Pre-emergence herbicides are important, but should be backed up with non-glyphosate knockdowns and strategic tillage; replacing a late-season, pre-emergence herbicide with inter-row tillage was predicted to delay glyphosate resistance by 4 years in awnless barnyard grass. (iv) Weed species' ecological characteristics, particularly seed bank dynamics, have an impact on the effectiveness of resistance strategies; S. oleraceus, because of its propensity to emerge year-round, was less exposed to selection with glyphosate than E. colona, resulting in an extra 5 years of glyphosate usefulness (18 v. 13 years) even in the most rapid cases of resistance evolution. Delaying tactics are thus available that can provide some or many years of continued glyphosate efficacy. If glyphosate-resistant cotton cropping is to remain profitable in Australian farming systems in the long-term, however, growers must adapt to the probability that they will have to deal with summer weeds that are no longer susceptible to glyphosate. Robust resistance management systems will need to include a diversity of weed control options, used appropriately.

Item Type:Article
Business groups:Crop and Food Science
Keywords:FF005Field Crops (NEW March 2000) FF020Plant Breeding and Genetics FF500Weeds and Noxious Plants HH410Pesticide and Drug Resistance JJ100Soil Biology JJ900Soil Management WW100 ZZ100Mathematics and Statistics 38641-94-0 1071-83-6 70393-85-0 cotton fallow genetic engineering genetic transformation glyphosate herbicide resistance herbicide resistant weeds herbicides resistance management seed banks simulation models tillage transgenic plants weed control weeds Australia Echinochloa colona Gossypium plants Sonchus oleraceus APEC countries Australasia Oceania Commonwealth of Nations Developed Countries OECD Countries Echinochloa Poaceae Cyperales monocotyledons angiosperms Spermatophyta plants eukaryotes Malvaceae Malvales dicotyledons Sonchus Asteraceae Asterales
Subjects:Plant pests and diseases > Pest control and treatment of diseases. Plant protection
Plant culture > Field crops > Textile and fibre plants
Science > Invasive Species > Plants > Effect of herbicides
Deposited On:21 Aug 2014 03:06
Last Modified:21 Aug 2014 03:06

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